Voltage and temperature sensor for a serializer/deserializer communication application

ABSTRACT

The present invention relates to integrated circuits. More specifically, embodiments of the present invention provide methods and systems for determining temperatures of an integrated circuit using an one-point calibration technique, where temperature is determined by a single temperature measurement and calculation using known electrical characteristics of the integrated circuit.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/021,955, filed Sep. 9, 2013, which is a continuation-in-partpatent application to the U.S. patent application Ser. No. 13/802,219,entitled “VOLTAGE AND TEMPERATURE SENSOR FOR A SERIALIZER/DESERIALIZERCOMMUNICATION APPLICATION”, filed 13 Mar. 2013, which is incorporated byreference herein for all purposes.

BACKGROUND OF THE INVENTION

The present invention relates to integrated circuits. More specifically,embodiments of the present invention provide methods and systems fortemperature calibration and determination of an integrated circuit usinga one-point calibration technique, where temperature is calibrated by asingle temperature measurement and temperature determination isperformed using known electrical characteristics of the integratedcircuit.

Integrated circuits have proliferated through the years. As featuresizes become smaller, certain types of devices have become larger,leading to temperature related problems. That is, a large networking orprocessing device consumes a large amount of power, which is oftendissipated as thermal energy such as heat. Heat is problematic and isdesirably to be controlled and monitored. Unfortunately, conventionaldevices often lack suitable thermal sensing devices. That is,conventional temperature sensing devices are non-existent in manyintegrated circuit devices. At best, conventional sensing devices oftenuse a diode device to monitor current information to extract temperatureinformation from other non-integrated integrated circuit devices. Thediode device is configured with an analog to digital convert to transmitthe temperature information. The converter is often expensive, large,and difficulty to scale and manufacture in an efficient manner. Otherlimitations include difficulty in calibration, monitoring, and oftenrequire multi-point calibration, which leads to additional costs duringthe manufacture of the integrated circuit.

From the above, it is seen that techniques for improving temperaturesensing and monitoring integrated circuits are highly desirable.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to integrated circuits. More specifically,embodiments of the present invention provide methods and systems fordetermining temperatures of an integrated circuit using a one-pointcalibration technique, where temperature is determined by a singletemperature measurement and calculation using known electricalcharacteristics of the integrated circuit.

Benefits are achieved over conventional techniques. Among other things,temperature calibration and determination can be performed by usingmeasurements of corresponding electrical characteristics, such asvoltage, current, delay, and/or others. Measuring electricalcharacteristics is usually faster and easier than measuring temperature.In addition, by using a single-point calibration method, the amount oftime (which translates to manufacturing costs) of calibrating thetemperature sensor is greatly reduced. It is to be appreciated thatembodiments of the present invention are compatible with existingcircuits and devices.

The present invention achieves these benefits and others in the contextof known memory technology. However, a further understanding of thenature and advantages of the present invention may be realized byreference to the latter portions of the specification and attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following diagrams are merely examples, which should not undulylimit the scope of the claims herein. One of ordinary skill in the artwould recognize many other variations, modifications, and alternatives.It is also understood that the examples and embodiments described hereinare for illustrative purposes only and that various modifications orchanges in light thereof will be suggested to persons skilled in the artand are to be included within the spirit and purview of this process andscope of the appended claims.

FIG. 1 is a simplified block diagram of a system on a chip integratedcircuit device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a sensing device with a multiplexeraccording to an embodiment of the present invention.

FIG. 3 is a simplified flow diagram illustrating the operation of asensing device according to embodiments of the present invention.

FIG. 4 is a simplified diagram illustrating a temperature sensor systemaccording to an embodiment of the present invention.

FIG. 5 is a simplified flow diagram illustrating a process forcalibrating a temperature sensor according to an embodiment of thepresent invention.

FIG. 6 is a simplified graph illustrating one point error calculationaccording to embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to integrated circuits. More specifically,embodiments of the present invention provide methods and systems fordetermining temperatures of an integrated circuit using a one-pointcalibration technique, where temperature is determined by a singletemperature measurement and calculation using known electricalcharacteristics of the integrated circuit.

An integrated circuits such as SerDes typically have multiple locationsthat may heat up to a temperature greater than the optimal operatingtemperature. In various embodiments, the present invention providessensing techniques for measuring these locations. FIG. 1 is a simplifiedblock diagram of a system on a chip integrated circuit device accordingto an embodiment of the present invention. This diagram is merely anexample, which should not unduly limit the scope of the claims. One ofordinary skill in the art would recognize many variations, alternatives,and modifications. As shown in FIG. 1, an integrated circuits comprisesmultiple locations that may need temperature and voltage sensing. Forexample, the integrated circuit in FIG. 1 is a SerDes device thatincludes a receiver and a transmitter, and it also has receiving lanes(e.g., RX Lanes) and transmission lanes (e.g., TX lanes). Sensors 102and 108 are positioned within a proximity of TX lanes at the receiverend. Sensors 104 and 106 are positioned within a proximity of TX lanesat the transmission end. Sensors 103 and 107 are positioned at thecenter portion of the integrated circuit. For example, the sensorsdetect temperature and/or voltage information and send the informationto the voltage-temperature (VT) core 101 as current levels. The VT core101, as described below, is configured to process the currentinformation and generates a digital read out of temperature information.In various embodiments, the sensors are capable of measure temperaturefrom about 0 C to over 110 C.

It is to be appreciated that the VT core 101 can be integrated to theintegrated circuit. In addition to the SerDes device as shown, the VTcore 101 can be integrated with other types of devices, such as SerDesdevice, a DDR register device, a DSP device, a controller device, amicrocontroller device, an ASIC device, or others. For example, anintegrated communication device (e.g., SerDes device) is configured on asilicon bearing substrate. The device has a transmitter module and areceiver module, both of which are also configured on the siliconbearing substrate. Additionally, the device comprises a phase lock loopmodule that is also configured on the silicon bearing substrate. Adigital logic core is configured on the same silicon bearing substrateas components of communication device. A voltage and temperature sensingmodule (e.g., the VT core that connects to the sensors) is configured onthe substrate as well. An example of the voltage and temperature sensingmodule is illustrated in FIG. 2 and described below.

FIG. 2 is a block diagram of a sensing device with a multiplexeraccording to an embodiment of the present invention. This diagram ismerely an example, which should not unduly limit the scope of theclaims. One of ordinary skill in the art would recognize manyvariations, alternatives, and modifications. The voltage-temperature(VT) core 200 in FIG. 2 can be implemented as an integrated sensingdevice, and as shown receives a plurality of inputs from sensors (e.g.,sensors 102-108 in FIG. 1). In a specific embodiment, analog componentsof the VT core 200 are on regulated power supply that reduces thepossibility of introducing jitters.

In various embodiments, the VT core 200 and the sensors shown in FIG. 1are manufactured using the same processes (e.g., 40 nm process, 28 nmprocess, etc.) as the integrated circuit that they measure. The sensorinputs are representative of voltage and/or temperature readings in theform of current levels. The multiplexer 206 is a part of the VT core 200that allows the VT core 200 to selectively process the VT readings fromthe sensors one at a time. Depending on the application, the VT core 200can have a large number of sensors. The selected current information(i.e., representative of temperature and/or voltage) is received by thereference generator 208. For example, the reference generator 208 asshown comprises a comparator and provides an output voltage Vtrip. Thereference generator 208 is electrically coupled to the output of themultiplexer 206 and is configured to generate a signal proportional tothe current information.

The VT core 200 comprises, among other components, a clock device, whichis not shown in FIG. 2. The clock device is configured to generate atleast a first clock signal and a second clock signal. The second clocksignal is 180 degrees out of phase of the first clock signal. The VTcore 200 further comprises delay cores 203 and 204. The first delay core203 includes a first delay core output, and it is coupled to the clockdevice to receive the first clock signal. The second delay core 204 hasa second delay core output. The second delay core is configured toreceive the second clock signal. As shown in FIG. 2, the first delaycore 203 is coupled to the second delay core 204 and shares a commonfeedback voltage (Vcmfb). Delay cores 203 and 204 are both connected tothe common feedback signal. Together, the first delay core 203 and thesecond delay core 204 generate a differential signal that has a commonmode representing a temperature reading during the temperaturemeasurement mode, or a voltage reading during the voltage measurementmode. The lower portion of FIG. 2 provides a detailed view of delay core203. For example, the delay core 204 is similarly configured.

The VT core 200 also includes a common load feedback (CMFB) circuit 211.The CMFB circuit 211 provides the common feedback voltage Vcmfb, whichis coupled to the first delay core 203 and the second delay core 204.The CMFB circuit 211 is coupled to a voltage extractor 212. The voltageextractor 212 is also coupled to the outputs of the first delay core 203and the second delay core 204. For example, the voltage extractor 212comprises resistors configured in series. Depending on theimplementation, the voltage extractor 212 can have different loadconfigurations as well.

A common mode generator circuit 208 is coupled to the common loadfeedback circuit 211. The common mode generator circuit is configured tooperate in a voltage measurement mode or a temperature measurement mode.A load equalizer device 205 is coupled to the second delay core 204output and the common load voltage extractor 212 as shown.

A comparator device 202 is coupled to the first delay core 203 outputand the common load voltage extractor 212. The comparator device 202 isconfigured to convert a first waveform 210 from the common mode voltageextractor to a second waveform. As shown at the bottom portion of FIG.2, the first waveform 210 is a triangular waveform. The triangularwaveform, as illustrated in FIG. 2, is a function of Vref=Vtrip+i*R. Theprinciple of operation is described in more details below. With the helpof the reference generator 208 that provides Vtrip voltage, thetriangular waveform is provided from the delay core 203 and containscurrent information. Reading the triangular waveform and the Vtripvoltage (from the reference generator 208), the comparator 202 isconfigured to generate a square waveform (not shown in FIG. 2). Thesquare waveform from the comparator 202 and a clock signal are coupledtogether by the logic gate 201 to generate a pulse width modulatedsignal 209. The clock signal can be generated by a pulse widthgenerator. In a specific embodiment, the clock signal has a frequency ofgreater than 2 MHz. For example, the logic gate 201 is an AND gate. Theoutput from the logic gate 201 can be used as a data signal thatrepresents voltage and/or temperature reading of the sensors.

FIG. 3 is a simplified flow diagram illustrating the operation of asensing device according to embodiments of the present invention. Thisdiagram is merely an example, which should not unduly limit the scope ofthe claims. One of ordinary skill in the art would recognize manyvariations, alternatives, and modifications. For example, the methodillustrated in FIG. 3 can be implemented using the exemplary deviceshown in FIGS. 1 and 2, and various steps may be added, removed,repeated, modified, replaced, and/or overlapped. The method starts atstep 301. For example, a temperature and voltage sensing device isstarted and initiated at step 301. For example, certain variables and/orparameters of the sensing device may be calibrated and/or adjusted atstep 301. At step 302, current information from a remote sensing sitewithin the integrated circuit device is transferred to a referencegenerator. In an embodiment, a multiplexer is used to select differentcurrent information from a number of sensing devices. The currentinformation can be from one of many sensors that are connected to a VTcore, which includes a reference generator. For example, the referencegenerator is configured to provide a reference voltage that can be used.As described above, the remote sensing site is provided on a spatialportion of one of a plurality of integrated circuit modules provided onthe integrated circuit device. For example, the current information is avariable across an operating range of the integrated circuit device.

At step 303, the current information is received by the referencegenerator. The reference generator is configured to generate a signalproportional to the current information using the reference generator,at step 304. For example, the signal is a function of a referencevoltage, current information from the sensing site, and known resistance(or impedance) value of one or more electrical components of the VTcore. At step 305, the generated signal is transferred to a common modefeedback circuit, which is coupled to a first delay core and a seconddelay core. For example, the connections between the common feedbackcircuit and the delay cores are illustrated in FIG. 2. At step 306, anaverage voltage of a period waveform is adjusted using the generatedsignal at the common mode feedback. For example, the average voltage ofthe period waveform is a function of the reference voltage and currentinformation received from the sensing site. The periodic waveform isconverted to a PWM signal that is representative of the currentinformation at a comparator device, at step 307. For example, the PWMsignal can be generated by using the period waveform and a clock signal.The period waveform can be a triangular waveform, a square waveform, ora sinusoidal waveform. The PWM signal, depending on the need, may betransferred to a remote device that is not a part of the integratedcircuit.

The PWM signal can be processed and used to provide digital informationthat represents temperature and/or voltage information embedded in thecurrent information. In a specific embodiment, the pulse width modulatedsignal is received, and the pulse width modulated signal is used in acounter device to output digital information representative of thecurrent information. As described above, the current information isassociated with a temperature or a voltage of the remote sensing site.In an implementation, the pulse width modulated signal is received andprocessed by a low pass filter device.

In various embodiments, a calibration process is used to providetemperature calibration and measurement. During the calibration mode(which may be necessary as a one-time setup), the current reading fromthe sensor is calibrated to temperature reading. Running the constantcurrent source at known current level and obtain a current reading fromthe sensor at a known temperature, the relationship between currentreading and the temperature reading is determined. For example, a ratio(e.g., or referred to as “gain”) between the current (or other voltage,delay) reading and the temperature level is determined and stored forlater measurements. When measuring the temperature reading, the ratio ismultiplied with a temperature difference from a reference temperature.For example, the following formula is used:Temp=Tc+Gain*{Delay2−Delay1}

Voltage calibration and measurement processes are performed similarly asthe temperature calibration. A ratio (or “gain”) between current readingand the voltage level is determined and stored for later measurements.When measuring the voltage reading, the ratio is multiplied with avoltage difference from a reference voltage. For example, the followingformula is used:Voltage=1V+Gain*{Delay2−Delay1}

It is to be appreciated that the arrangement and implementation oftemperature sensors illustrated in FIGS. 1-3 can provide accuratereading, the method of using temperatures is an important aspect aswell. In various embodiments, the present invention provides techniquesfor quickly calibrating and determining temperature by relying on knownrelationship between electrical properties and temperature.

As explained above, temperature sensors are important in ensuring properoperation conditions for controls. For example, the integrated circuitdevice shown in FIG. 1 utilizes many temperature sensors so thattemperatures at different location can be determined as needed. It is tobe appreciated that the temperature sensor device in FIG. 2 is capableof determining temperature and providing the temperature readingquickly. But it is to be understood that it is important to have bothgood temperature sensing hardware and temperature sensing techniques.The temperature sensing techniques described below can be used inconjunction with the temperature sensing device in FIG. 2 and othertemperature sensing systems and devices as well.

For temperature sensor readings to be useful and reliable, temperaturesensors are calibrated before use. According to conventional techniques,calibrating temperature sensors requires temperature measurements at twoor more temperatures. Unfortunately, calibration at two or moretemperatures is a time consuming process. To measure an integratedcircuit device or a chip at two temperatures, it is necessary to changethe temperature of the subject (i.e., the integrated circuit) oftemperature measurement in order to measure it at a second temperature.It often takes a lot of time to change the temperature (e.g., controlledheating up or cooling down) of a subject device, thereby increasing themanufacturing time, which translates to lower manufacturing throughputand higher cost, as manufacturing time is a considerable portion of theintegrated circuit chip production cost.

According to embodiments of the present invention, temperature sensorscan be calibrated with one temperature measurement, thereby reducingmanufacturing costs. During the temperature determination process,values based on electrical characteristics are used to calibratetemperature sensor. More specifically, embodiments of the presentinvention use a value, current proportional to absolute temperature(IPTAT), to calibrate temperature at a single point. Among other things,the IPTAT value can be changed using one or more control switches. Forexample, IPTAT is sometimes referred to as Inversely Proportional toAbsolute Temperature. In a specific embodiment, a control module is useto cause changes in IPTAT value. It is to be appreciated that the IPTATvalue can be referred to in other terms as well. In a specificembodiment, IPTAT is a physical quantity whose value is equal tok*T*ln(M)/R, where “k” is Boltzmann's constant, “T” is absolutetemperature in Kelvin, “ln” is natural logarithm, “M” is a designconstant, and “R” is the resistance value of a resistor. For example,the design constant M is derived based on the electrical and physicalcharacteristics of the underlying integrated circuit and/or thetemperature sensor.

It is to be appreciated that IPTAT here is used as a reference value,which is used for calibration purpose. For temperature calibration,other reference values, or code reflecting the values, can be used aswell. In certain applications, it might be impractical to measure theIPTAT value. And in these applications, code values related to thetemperature sensor calibration can be used. Depending on theapplication, code values can be more robust than the IPTAT, which isrelated to current measurement. For example, to calibrate thetemperature sensor, one way is to change the IPTAT value by using thecontrol switch to change one or more parameters of the sensor and/or theunderlying device, at temperature T0.

For example, a new IPTAT value, IPTAT1, corresponds to a new temperature(or a new temperature equivalent). Similarly, a new code value, Code1,can also be used to correspond to a new temperature (or new temperatureequivalent), where a code value is used to reflect one or morecharacteristics of the temperature sensor and/or underlying device.

FIG. 4 is a simplified diagram illustrating a temperature sensor systemaccording to an embodiment of the present invention. This diagram ismerely an example, which should not unduly limit the scope of theclaims. One of ordinary skill in the art would recognize manyvariations, alternatives, and modifications. As shown in FIG. 4, thetemperature sensor system comprises a temperature sensor 401, aprocessor 403, and the control module 402. In various implementations,the temperature sensor 401, a processor 403, and the control module 402are implemented as a part of the integrated circuit devices whosetemperature is to be monitored.

The temperature sensor 401, as the name suggests, is configured to taketemperature readings as needed. The processor 403 is configure toprocess the temperature sensor readings, perform temperaturecalibration, and generate and use a line equation for temperaturedetermination. As described below, temperature reading can be determinedby using the line equation and value(s) associated with electricalcharacteristics (e.g., voltage, current, delay, and/or others). Thecontrol module 402 is configured to switch one or more operatingparameters associated with the temperature sensor. In a specificembodiment, the control module 402 is capable of causing changes inIPTAT value. For example, the control module 402 is connected to a IPTATcurrent generator. It to be appreciated that temperature sensor 401, aprocessor 403, and the control module 402 can be integrated as a singleunit (e.g., a part of an integrated temperature sensor) and/orimplemented using various types of hardware module. Additional modulesmay be used as well. For example, the temperature sensor system in FIG.4 may additionally include memory storage device that stores temperaturecalibration values, IPTAT values, line equations, temperaturecalibration and measurement instructions (executable by the processor403).

FIG. 5 is a simplified flow diagram illustrating a process forcalibrating a temperature sensor according to an embodiment of thepresent invention. This diagram is merely an example, which should notunduly limit the scope of the claims. One of ordinary skill in the artwould recognize many variations, alternatives, and modifications. Forexample, various steps may be added, removed, repeated, modified,replaced, rearranged, and/or repeated, which should not unduly limit theclaims.

For the purpose of temperature sensor calibration, an initial IPTATvalue, IPTAT₀ is to be determined. For IPTAT₀ value determination,calibration temperature T₀ and value(s) associated with electricalcharacteristics are needed.

At step 501, a value Q₀ is measure at the calibration temperature T₀.For example, the calibration temperature can be near room temperature,thereby allowing the integrated circuit to quickly reach T₀ for quickmeasurement. For example, to determine IPTAT₀, voltage, current, and/ordelay values corresponding to the calibration temperature T₀ aremeasured as well. For example, measured value of electricalcharacteristics (e.g., voltage, current, and/or delay) is denoted as Q₀.

At step 502, the IPTAT₀ is determined at the calibration temperature T₀.As explained above, the IPTAT₀ value can be-calculated from known “M”and “R” value, and one or more Q₀ value(s). It is to be appreciated thatthe IPTAT value determination may involve using other formulae and/orvariables as well.

For calibration to work, a second IPTAT value, IPTAT₁, is to bedetermined. As explained below, multiple (e.g., 2) IPTAT values areneeded to generate a linear equation that can be used for latertemperature determination. To cause the IPTAT value to change fromIPTAT₀ to IPTAT₁, control switches can be used to change one or moreelectrical characteristics (e.g., voltage, current, delay, and/orothers). At step 503, the IPTAT value is changed from IPTAT₀ to IPTAT₁,and corresponding current is changed accordingly. As mentioned above, acontrol module may be used to cause changes in the IPTAT value. Thechange from IPTAT₀ to IPTAT₀ can be made quickly and within a timeperiod the temperature is still at (or very close to) temperature T₀.For the purpose of calibration, an equivalent temperature T₁corresponding to the IPTAT₁ is determined.

At step 504, a new temperature T₁ is determined. As explained above, theactual temperature corresponding to IPTAT₁ and current is substantiallythe same as T₀. However, for the purpose of temperature calibration,current value and IPTAT₁ correspond to the new temperature T₁. Eventhough the actual or operating temperature has not changed, temperaturesensor is operating at a new “equivalent” temperature because of thechange of IPTAT. Similarly, if code value is used instead of IPTAT, theequivalent temperature calculation is performed using the code value.

The new“equivalent” temperature is calculated as below:T ₁ =T ₀*(IPTAT₁/IPTAT₀)  (Equation 1)

And in case code value is used:T ₁ =T ₀*(Code₁/Code₀)  (Equation 1A)

Corresponding to the change of IPTAT from IPTAT₀ to IPTAT₁, the valueassociated with the one or more electrical characteristics Q₁ ismeasure. For example, Q₁ can be voltage, current, delay, or other valuethat corresponds to T₁.

At step 506, a gain value “G” of the temperature sensor is determined.More specifically, the gain (“G) of the temperature sensor is calculatedusing the equation below:G=(Q ₁ −Q ₀)/(T ₁ −T ₀)  (Equation 2)

At step 507, a line equation is provided. Among other things, the lineequation can used to provide temperature reading by reading one or morevalues corresponding to electrical characteristics. In a specificembodiment, the line equation of the temperature sensor is calculatedas:Q(T)=G*(T−T ₀)+Q ₀  (Equation 3)

For example, to obtain a temperature measurement T_(m), Equation 3 andthe electrical characteristics can be used. A reading of an electricalcharacteristics (e.g., voltage, current, delay, and/or others), orQ_(m), that corresponds to actual temperature is determined. Thefollowing equation is used to obtain the temperature measurement T_(m):T _(m) ={Q(T _(m))+G*T ₀ −Q ₀ }/G.  (Equation 4)

It is to be appreciated that temperature can quickly be re-calibratedand determined using Equation 4, as electrical characteristics aretypically easier to determine than temperature reading. For example, themethod illustrated in FIG. 4 can be implemented using the temperaturesensor system in FIG. 4.

To provide an example, temperature calibration is performed using, amongother things, the delay characteristic at calibration temperature T_(c):

$I_{1} = {{{IPTAT}({Tc})} = \frac{{kTc}*{\ln(M)}}{q*R\; 1}}$

At a second IPTAT value, or IPTAT(Tc+ΔT₂) is:

$I_{2} = {{{IPTAT}\left( {{Tc} + {\Delta\; T_{2}}} \right)} = \frac{{k\left( {{Tc} + {\Delta\; T\; 2}} \right)}*{\ln(M)}}{q*R\; 1}}$

Or changing the calibration code “m” times so that:

$I_{2} = {{{IPTAT}\left( {{Tc} + {\Delta\; T_{2}}} \right)} = \frac{{m({kTc})}*{\ln(M)}}{q*R\; 1}}$

The temperature change (equivalent) based on “delay2” can by determinedby:

${\Delta\; T_{2}} = {{Tc}*\left( {\frac{{IPTAT}\left( {{Tc} + {\Delta\; T\; 2}} \right)}{{IPTAT}({Tc})} - 1} \right)}$

Similarly, a third IPTAT value, IPTAT(Tc+ΔT₃) is:

$I_{3} = {{{IPTAT}\left( {{Tc} + {\Delta\; T_{3}}} \right)} = \frac{{k\left( {{Tc} + {\Delta\; T\; 3}} \right)}*{\ln(M)}}{q*R\; 1}}$

Or changing the calibration code “n” times so that:

$I_{3} = {{{IPTAT}\left( {{Tc} + {\Delta\; T_{3}}} \right)} = \frac{{n({kTc})}*{\ln(M)}}{q*R\; 1}}$

The temperature change (equivalent) based on “delay3” can by determinedby:

${\Delta\; T_{3}} = {{Tc}*\left( {\frac{{IPTAT}\left( {{Tc} + {\Delta\; T\; 3}} \right)}{{IPTAT}({Tc})} - 1} \right)}$${\Delta\; T} = {{Tc}*\left( \frac{{l\; 3} - {l2}}{l1} \right)}$Δdelay=delay3−delay2

And therefore, the temperature change relative to the delay value is:

${TempGain} = \frac{\Delta\;{delay}}{\Delta\; T}$

It is to be appreciated that the use of gain factor and linear equationto obtain temperature reading is an interpolation process, who error ischaracterized by Equation 5 below:Error=Delay(T)−{Gain_(1pt)×(T−Tc)+Delay(T)|_(T=Tc)}  (Equation 5)

FIG. 6 is a simplified graph illustrating one point error calculationaccording to embodiments of the present invention. This diagram ismerely an example, which should not unduly limit the scope of theclaims. One of ordinary skill in the art would recognize manyvariations, alternatives, and modifications.

As explained above, one-point temperature calibration process can moreefficient and cost-effective compared to conventional two-pointcalibration processes. Tables below are provided to compare thetemperature determined by one-point calibration process according to animplementation of the present invention to temperature determined usingconventional two-point calibration technique.

Table 1 below shows junction temperature calculation from chambertemperature and power consumption

Junction Temperature Calculation from Chamber Temperature and PowerConsumption

TABLE 1 Chip Chamber Temp [° C.] Power [W] ΔT [° C.] Junction Temp [°C.] −9.8 1.842 13.44 3.64 −0.1 1.877 13.70 13.60 10.2 1.985 14.49 24.6920.3 1.923 14.04 34.34 27 2.114 15.43 42.43 40.1 1.975 14.42 54.52 502.032 14.83 64.83 59.9 2.174 15.87 75.77 70 2.120 15.48 85.48 79.6 2.26516.53 96.13 89.9 2.320 16.93 106.83

As shown in Table 1, the ambient chamber temperature is adjusted, andpower is measure. Then the junction temperature is calculated. Forexample, the equivalent temperature is calculated using the techniquesaccording to embodiments of the present invention.

In comparison, conventional two-point temperature calibration requires achange in junction temperature, as illustrated in Table 2 below:

TABLE 2 Junction Temp [° C.] Delay Temp Error 3.64 43.75272727 3.64 0.0013.60 51.32412121 14.86 1.26 24.69 59.26787879 26.64 1.94 34.3465.47393939 35.83 1.50 42.43 69.94230303 42.45 0.02 54.52 77.0172121252.94 −1.58 64.83 86.26424242 66.64 1.81 75.77 93.58739394 77.50 1.7385.48 100.2278788 87.34 1.86 96.13 106.0615758 95.98 −0.15 106.83113.3847273 106.83 0.00

In a conventional two-point calibration process, junction temperature ischanged and the corresponding delay is measured. By using therelationship between the delay value and the junction temperature, gainand offset values for the system can be determined for the two-pointcalibration method. The gain and offset values, once determined, providea basis for the line equation associated with the temperature sensorsystem. The line equation can then be used to determine junctiontemperature value.

Table 3 illustrates a process of using code value to perform one-pointtemperature calibration:

TABLE 3 1Point Calibration Code Equivalent Temp [° C.] Delay (ns) 0 0 10 12.39 49.33818182 0 0 1 1 27.41 58.70933333 0 1 0 0 (Default) 42.4369.94230303 0 1 0 1 57.46 79.12727273 0 1 1 0 72.48 89.49139394 0 1 1 187.50 99.3590303 1 0 0 0 102.52 110.4678788 1 0 0 1 117.54 119.5907879Gain1Point Offset1Point 0.673 40.78

As illustrated in Table 3, calibration code value is changed. Based onthe change in calibration code value, the equivalent temperature valueis determined. The delay value (measure in nanosecond) is also measured.Using the calibration code value, equivalent temperature, and delayvalue, gain and offset value for the one point calibration equation canbe determined.

Table 4 below illustrates using the one-point calibration equationdetermined from Table 3 to determine junction temperature:

TABLE 4 Junction Temp [° C.] Temp [° C.] Error [° C.] 3.64 4.42 0.7713.60 15.67 2.06 24.69 27.47 2.78 34.34 36.69 2.36 42.43 43.33 0.9054.52 53.84 −0.67 64.83 67.58 2.75 75.77 78.47 2.70 85.48 88.33 2.8696.13 97.00 0.87 106.83 107.88 1.05

For example, the gain value and offset value determined from Table 3 isused to provide a line equation, which is then used to provide junctiontemperature information based on other known values. It is to beappreciated that while the junction temperature determined using thelinear equation determined using an one-point calibration method isslightly different from the actual temperature, the amount of error isrelatively small and acceptable for most of the application where atemperature reading is needed.

It is also to be noted that the amount of error from an exemplaryone-point calibration method is comparable to the amount of error from aconventional two-point calibration method, as illustrated in Table 5below:

TABLE 5 Error_2PointCalibration [° C.] Error_1PointCalibration [° C.]0.00 0.77 1.26 2.06 1.94 2.78 1.50 2.36 0.02 0.90 −1.58 −0.67 1.81 2.751.73 2.70 1.86 2.86 −0.15 0.87 0.00 1.05

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. Therefore, the above description and illustrations should not betaken as limiting the scope of the present invention which is defined bythe appended claims.

What is claimed is:
 1. A method comprising: measuring a firsttemperature on an integrated circuit using a temperature sensor;determining a first reference value for the integrated circuit at thefirst temperature, the reference value based on a first delay electricalcharacteristic; measuring a second delay electrical characteristic forthe integrated circuit; determining a second reference value for theintegrated circuit based on the second delay electrical characteristicand a second temperature; determining a gain value from the firstreference value and the second reference value; generating a lineequation using the gain value; measuring a third delay electricalcharacteristic comprising a differential signal from a delay core; anddetermining a third temperature using the third delay electricalcharacteristic and the line equation.
 2. The method of claim 1 whereinthe first reference value is proportional to current.
 3. The method ofclaim 1 wherein the first reference value is proportional to the firsttemperature.
 4. The method of claim 1 wherein the second temperature isa new equivalent temperature.
 5. The method of claim 1 furthercomprising generating the second reference value using one or morecontrol switches.
 6. The method of claim 1 wherein the gain value is aratio between a changing electrical characteristic and a correspondingchanging temperature.
 7. The method of claim 1 wherein the firstreference value comprises a current proportional to absolute temperaturevalue described by equation IPTAT=K*T*ln(M)/R, where K is Boltzmann'sconstant, T is absolute temperature in Kelvin, M is a design constant,and R is a resistance value.
 8. The method of claim 1 wherein theintegrated circuit comprises a Serializer/Deserializer (SerDes) device,a DDR register device, a DSP device, a controller device, amicrocontroller device, or an ASIC device.
 9. The method of claim 1wherein: the delay core comprises a first delay core and a second delaycore receiving a common feedback voltage; and the differential signal isfrom the first delay core and the second delay core.
 10. A systemcomprising: a temperature sensor positioned on an integrated circuit andassociated with a reference value and a line equation for determining atemperature value; a control element configured to change one or morevariables of the reference value; a processor configured to determinethe temperature value using at least the line equation; wherein: thereference value is proportional to the temperature value; the lineequation is determined by calculating a gain factor, the gain factorbeing based on change in temperature corresponding to change in the oneor more variables caused by the control element; the processordetermines the temperature value using reading of one or more delayelectrical characteristics comprising a signal from a delay core that isincluded in the temperature sensor.
 11. The system of claim 10 whereinthe temperature sensor is configured to determine delay values.
 12. Thesystem of claim 10 further comprising a memory element for storing atleast the reference value.
 13. The system of claim 10 further comprisingan interface for transmitting the temperature value.
 14. The system ofclaim 10 wherein the first reference value comprises a currentproportional to absolute temperature value described by equationIPTAT=K*T*ln(M)/R, where K is Boltzmann's constant, T is absolutetemperature in Kelvin, M is a design constant, and R is a resistancevalue.
 15. The system of claim 14 further comprising a memory storingcharacterization data associated with the integrated circuit, thecharacterization data comprising the design constant.
 16. The system ofclaim 10 wherein the temperature value is determined using a basereference temperature value.
 17. The system of claim 10 wherein: thedelay core comprises a first delay core and a second delay corereceiving a common feedback voltage; and the signal comprises adifferential signal from the first delay core and the second delay core.18. The system of claim 10 wherein the integrated circuit comprises aplurality of temperature sensors at different locations.
 19. The systemof claim 18 wherein the integrated circuit comprises aSerializer/Deserializer (SerDes) device having a first temperaturesensor at a receiver and a second temperature sensor at a transmitter.20. The system of claim 10 wherein the integrated circuit comprises aDDR register device, a DSP device, a controller device, amicrocontroller device, or an ASIC device.